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Re: Running out of ideas: stability, bootstrap

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On a sunny day (Mon, 29 May 2017 11:44:20 -0400) it happened bitrex
<bitrex@de.lete.earthlink.net> wrote in <olXWA.100487$df3.20124@fx30.iad>:

>On 05/29/2017 11:36 AM, Jan Panteltje wrote:
>
>> I looked at it twice and declined to comment as I
>> 1) have no idea what it does.
>> 2) have no idea what it is supposed to do.
>> 3) have no idea why make a peeseebee for something that one has not tested.
>> 4) looks overly complicatiaotiantiated to me, brain abort.
>> 
>
>Yeah, this is why I don't feel too bad if my suggestion wasn't on the mark.
>
>I know I'm guilty of this myself sometimes, but while people are very 
>familiar with their own designs I don't think everyone else can 
>immediately intuit what's going on in a circuit that has say, more than 
>a couple transistors or op amps. A few sentences of explanation of 
>what's _supposed_ to happen would help OP a lot before jumping right 
>into what the problems are with...whatever it is.
>
>My impression was that it's a cascode source follower with U1A acting as 
>a post amplifier, then feeding an integrator which then feeds the FET 
>gate resistor. Holding the collector of the top cascode transistor at 
>virtual ground by tying it to the op amp inverting input is clever, but 
>it also seems sketchy as the only way U1A has to hold it there is around 
>the loop to the FET gate. Transimpedance amp-connected op amp -> 
>integrator is at least 270 degrees of phase shift at high frequency 
>right off the bat. Seems sketch.

Yes, and there is more we need to know, drive impedance, requirements,
I posted long ago here about my (accidently discovered) better alternative
vidicon preamp (better than the common bootstrap circuit).
It all depends...

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Running out of ideas: stability, bootstrap Gerhard Hoffmann <ghf@hoffmann-hochfrequenz.de> - 2017-05-28 17:11 +0200
  Re: Running out of ideas: stability, bootstrap bitrex <bitrex@de.lete.earthlink.net> - 2017-05-28 12:09 -0400
    Re: Running out of ideas: stability, bootstrap Gerhard Hoffmann <ghf@hoffmann-hochfrequenz.de> - 2017-05-28 23:01 +0200
      Re: Running out of ideas: stability, bootstrap Jim Thompson <To-Email-Use-The-Envelope-Icon@On-My-Web-Site.com> - 2017-05-28 14:30 -0700
        Re: Running out of ideas: stability, bootstrap Gerhard Hoffmann <ghf@hoffmann-hochfrequenz.de> - 2017-05-28 23:56 +0200
          Re: Running out of ideas: stability, bootstrap Jim Thompson <To-Email-Use-The-Envelope-Icon@On-My-Web-Site.com> - 2017-05-28 15:08 -0700
  Re: Running out of ideas: stability, bootstrap John Larkin <jjlarkin@highlandtechnology.com> - 2017-05-28 09:46 -0700
    Re: Running out of ideas: stability, bootstrap Gerhard Hoffmann <ghf@hoffmann-hochfrequenz.de> - 2017-05-28 22:09 +0200
      Re: Running out of ideas: stability, bootstrap Joerg <news@analogconsultants.com> - 2017-05-29 07:13 -0700
        Re: Running out of ideas: stability, bootstrap dagmargoodboat@yahoo.com - 2017-05-29 20:56 -0700
          Re: Running out of ideas: stability, bootstrap Winfield Hill <hill@rowland.harvard.edu> - 2017-05-30 03:55 -0700
            Re: Running out of ideas: stability, bootstrap Gerhard Hoffmann <ghf@hoffmann-hochfrequenz.de> - 2017-05-30 15:53 +0200
              Re: Running out of ideas: stability, bootstrap dagmargoodboat@yahoo.com - 2017-05-30 10:42 -0700
  Re: Running out of ideas: stability, bootstrap bitrex <bitrex@de.lete.earthlink.net> - 2017-05-29 08:38 -0400
    Re: Running out of ideas: stability, bootstrap bitrex <bitrex@de.lete.earthlink.net> - 2017-05-29 08:40 -0400
    Re: Running out of ideas: stability, bootstrap Gerhard Hoffmann <ghf@hoffmann-hochfrequenz.de> - 2017-05-30 16:51 +0200
  Re: Running out of ideas: stability, bootstrap Winfield Hill <hill@rowland.harvard.edu> - 2017-05-29 07:36 -0700
    Re: Running out of ideas: stability, bootstrap bitrex <bitrex@de.lete.earthlink.net> - 2017-05-29 11:20 -0400
      Re: Running out of ideas: stability, bootstrap Jan Panteltje <pNa0nStpealmtje@yahoo.com> - 2017-05-29 15:36 +0000
        Re: Running out of ideas: stability, bootstrap bitrex <bitrex@de.lete.earthlink.net> - 2017-05-29 11:44 -0400
          Re: Running out of ideas: stability, bootstrap bitrex <bitrex@de.lete.earthlink.net> - 2017-05-29 11:53 -0400
          Re: Running out of ideas: stability, bootstrap Jan Panteltje <pNa0nStpealmtje@yahoo.com> - 2017-05-29 17:01 +0000
        Re: Running out of ideas: stability, bootstrap Winfield Hill <hill@rowland.harvard.edu> - 2017-05-29 08:46 -0700
          Re: Running out of ideas: stability, bootstrap Jan Panteltje <pNa0nStpealmtje@yahoo.com> - 2017-05-29 16:56 +0000
      Re: Running out of ideas: stability, bootstrap dagmargoodboat@yahoo.com - 2017-05-29 21:12 -0700

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